[BIOSAL] Code review

[Boisvert, Sebastien]

Here is a review of your acquaintance code at
https://github.com/gkthiruvathukal/biosal/tree/granularity/examples/hello_acquaintances

Last commit: dd008cda0b


- This code will hang because an actor may have received ACTION_STOP from itself before
it receives ACTION_HELLO_GREET_OTHERS from another actor. Sending a message to a dead actor does 
nothing -- the message is never received.

- print_core_vector_int does the same thing as core_vector_print_int.

- in the ACTION_START block, you are sending ACTION_HELLO_GREET_OTHERS from an actor to itself

- in the ACTION_HELLO_GREET_OTHERS block, you unpack in a vector that already contains information.
This is fine since unpack is not a constructor though, so no worry.